Sha of Fear : Healing on the platforms as a Holy Priest

Hi everyone.

Tommorow night, we've tried Sha of Fear (25 N). Yet, as a Holy Priest, I encountered some problems maintaining my health group high, healing myself and catching the orbs on the platforms. My Divine Hymn seemed to be useless to deal with the Crossbowmen's Death Blossom, and I eventually died from it.
I was in Chakra : Sanctuary, but not entirely satisfied with its usefulness. I wonder if being in Chakra : Serenity would help at all.

I'd like to know how you manage this phase as a Holy Priest, or as a healer, whatever your class is.